Hydraulic press.



PATENTED JULY 5, 1904.

EL (ROWB.V

HYDRAULIC PRESS.

APPLICATION 111mm Nov. a', loos..

-N0 MODEL.

UNITED STATES Patented July 5, 19U4.

PATENT OFFICE.

VEDWARD OROWE, OF SHEEFIELD, ENGLAND, ASSIGNOR OF ONE-HALF TO DAVY BROS., LIMITED, OF SI-IEFFIELD, ENGLAND, AN INCORPORATED' COMPANY.

HYDRAULIC PF1 ESS.

SPECIFICATION forming part of Letters Patent No. 764,522, dated July 5, 1904,

l i Original application filed Juno l5, 1903, Serial No. 161,538. Divided and this application filed November 3, 1903. Serial No.1'79,699. (No model.)

To all tf1/1,0m it may cm1/cern,.-

Be it known that I, EDWARD OROWE, engineer and chief draftsman, a subject of the King of Great Britain, residing at Birchholm,

5 Bushey VVood,Totley,Rise, Sheffield, England,

have invented certain new and useful Improvements in Hydraulic Presses, of which the following is a specilication.

This invention relates to hydraulic presses ro for forging and for other purposes-such, for

example, as bending and testing armor-plates, iianging` and the likein which the power for lifting the press-head is supplied from an accumulator or other source independent of that from which the power is derived for causing the press-head to perform its work.

The invention has for its object to' effect economy of time and power, and so increase the speed of working' and the efficiency of the 2o press. This end is attained mainly by the provision of means wherebythe idle descent of the press-head onto its work may be effected quickly and by gravity alone and whereby the power of the pumps is caused to z5 come into action automatically immediately the tool carried by the press-head encounters the work.

The present application is a division of my copending application, Serial No. 161, 538, filed June 15, 1903.

Reference is to be had to the accompanying drawings, wherein- Figure 1 shows in an elementary form the improved apparatus and arrangement of parts,

3 5 the two portions of theiigure being drawn to different scales. Fig. 2 shows a detail drawn to a larger scale.

The press comprises a main cylinder A and ram B (one or more) for imparting the work- 40 ing stroke to the press-head and lifting' cylinders G and pistons D for imparting the return stroke. The pipe connections with these cylinders are controlled by valves arranged to so operate that during the idle descent of the press-head the main and lifting' cylinders can be connected at the same time with their respective exhaust in such manner that the main cylinder A, being permitted to draw from the exhaust-tank, will descend freely by its own weight, the main pumps meanwhile either running. light or being' out of Work, while during the working portion of the pressstroke pressure can be supplied to the main cylinder A and exhausted from the lifting'- cylinders O and on the return stroke can be supplied to the lifting-cylinders O and exhausted from the main cylinder A alternatively.

Between the main cylinder A and the exhaust-valve F there is provided a self-closing by-pass suction-valve G, which while permitting the main cylinder to draw from the exhaust during the free descent of the presshead will be closed immediately the descentof the main ram is checked in consequence ofthe 6 5 tool meeting the work, so that pressure then brought to bear on the main ram will cause its descent to be continued, but at a slower speed.

The upper end of the main cylinder A is connected by a pipe a with the valve-box ofthe valvesGrandFand through a constantly-open annular passage f around the latter valve with the delivery-pipe p from the pumps P.

Pressure from an accumulator (or other' 75 source of power independent of that from which the power is derived for causing the press-head to perform its work) is admitted to the lifting-cylinders O by way of the pipe c and branches c', the supply to and exhaust 8O from pipe c being controlled by means of a slide-valve H, worked by a lever-handle L, as shown. The lever L is also connected to the spindle if?, controlling the action of the main exhaust-valve E, so that when the valve H is moved to admit pressure to the lifting-cylinders lO the main exhaust-valve E will be opened and, alternatively, when the valve l-I is moved to connect the lifting-cylinders (l with their exhaust the main exhaust-valve E will be closed.

The exhaust-valveF is a piston-valve of two diameters, the upper portion, which works in the cylinder f, being of larger diameter than the valve-face itself, so that the valve will be opened by pressure acting upon the annular shoulder representing the diiferenoe between the two diameters when, as hereinafter explained, such pressure exceeds that normally tending to hold the Valve closed.

The valve F is provided with a pilot-valve K, worked by the spindle 7a2, whichis connected to the lever-handle L, already mentioned. the pilot-valve K controlling an orifice leading to the exhaust from the chamber in which the valve K works. The pilot-Valve face is of the same diameter as the upper part of the spindle k2, so that the valve Kitself is balanced, and therefore easy to open. The spindle 702 carries guides 1, working within a chamber in the exhaust-valve F, this chamber being in free communication with the cylinderf above the Valve F, while small holes lo', drilled through the side of the valve F, maintain communication between the said chamber and the annular space f, surrounding the body of the valve F, as already described. The collective area of the holes is so much less than that of the orifice closed by the pilotvalve K that when the latter is'open the water can escape more quickly than it can enter, the action being as follows: Supposing the valves F and K to be closed, the former will bekept firmly closed by the pump-pressure transmitted through the holes It" and acting on the top of valve F. On the pilot-valve K being opened the pressure tending to hold valve F to its seat will be relieved, and the pressure from the main press-cylinder A acting in the annular passage f upon the area of the valve F corresponding to the difference of its two diameters will cause the valve F to rise until the area of the relief-passage through valve K is so diminished as to equal only the collective area of the holes f, and consequently so long as there is suiicient pressure from the main press-cylinder A acting in the passage f the valve F will be caused to follow the upward motion of the pilot-valve K.

When once the valve F is wide open, there will be no pressure in the system, and consequently there will be no resistance to overcome in closing this valve.

In a downwardly-acting hydraulic press wherein working and lifting rams are connected to the press-head, the lifting-rams being operated by pressure from an auxiliary source of supply independent of that which supplies power to the working ram, the combination of a valve for controlling the exhaust from the cylinder of the working ram, the body of said exhaust-valve being formed as a plunger of two diameters fitted to Workin a cylinder wherein it presents a dierence of area to the action of the working pressure; av

chamber within the body of said exhaust-valve in constant communication with the source of working pressure; a balanced pilot-valve f1tted to work in said chamber and adapted to control an orifice leading therefrom to the exhaust; a hand-operated valve for 'controlling the admission to and exhaust from the liftingcylinders of the auxiliary pressure; a rnechanical connection between said valve and the pilot-valve such that when the former is in position to admit auxiliary pressure to the EDWARD CROWE.

Witnesses:

BAN. L. CAMPBELL, LUTHER J. PARR. 

